Digital cameras and digital video cameras have been applied in life in a large scale. In current applications, the digital cameras based on Charge Coupled Devices (CCDs) occupy most of the market, and most of the digital cameras adopt the interlaced scanning technology. In a conventional interlaced CCD image sensor, each frame of image (2N rows) can be divided into a top field (N odd rows) and a bottom field (N even rows). When image processing is performed, exposure, electric charge accumulation, and image enhancement and output are performed on a top field image and a bottom field image successively.
In a video image processing method in the prior art, usually, exposure is performed with a frame as a unit. For example, a video processing technique in the prior art is as follows.
Step A: Acquire a video sequence, and set long exposure and short exposure alternately with a frame as a unit.
Step B: Match and align each pixel of a current frame to a pixel position in a next frame pixel by pixel, and find a most credible pixel from each matched pixel set.
Step C: Use brightness and color information of the pixel to calculate a luminance map.
Step D: Use a tone mapping method to compress the high-bit luminance map into an 8-bit image.
During the research and practice of the prior art, the inventors of the present invention find that for scenarios (for example, a high dynamic range scenario) of complex brightness distribution, scenarios of low illumination, scenarios of highlight shooting, and scenarios of backlight shooting, single exposure using each frame as a pixel unit is incapable of recording a scenario accurately, thereby resulting in degradation of imaging quality.